The present invention relates generally to the field of oxygen scavenging packaging. In particular it relates to oxygen scavenging compositions in which oxygen scavenging is catalyzed by certain transition metal carboxylates.
It is known that limiting the exposure of oxygen-sensitive products to oxygen can maintain and enhance the quality and shelf-life of the products. One technique for limiting oxygen exposure involves incorporating an oxygen scavenger into the packaging structure for a product. Incorporation of a scavenger in the package can allow for removal of (a) oxygen present in the interior when product is filled into the package, or (b) oxygen that migrates into the package after product is filled into the package, thereby maintaining a low level of oxygen throughout the package.
In many cases, however, the onset of oxygen scavenging in this system does not occur for days or weeks. In addition, the rate of oxygen scavenging can also be relatively low. The onset of oxygen scavenging can be accelerated and the rate at which it occurs can be increased by the use of transition metal salts with organic counterions as catalysts for oxygen scavenging in a packaging article. These metal salts can be used in multilayer-film packaging applications in either an oxygen scavenging layer or a layer adjacent to an oxygen scavenging layer. However, oxygen scavenging packaging comprising transition metal catalysts having certain organic counterions, such as cobalt oleate and cobalt stearate, can have negative organoleptic effects on packaged oxygen-sensitive materials. In particular, taste and odor problems sometimes occur. Though not to be bound by theory, these organoleptic problems may be caused by the breakdown of the organic counterions (e.g., oleate and stearate).